I would recommend just using the Python provided by osx. "-framework Python" on the gcc command line to compile/link.

You can emerge mysql and it should give you the shared libraries you are wanting. I would recommend CompleteMysql, http://www.serverlogistics.com/mysql.php. I am not saying that gentoo won't work fine, but CompleteMysql gives you a very nice preference pane for administrating mysql on OSX.